Generally, solar energy is clean energy which does not generate any air pollution, noise, heat generation, vibration, etc. The solar energy does not require fuel transport and maintenance of power generating facilities, and in the solar energy, it is easy to select a place for installation of facilities, the scale of the facilities may be freely chosen, the lifespan of the facilities is long, and the installation is easy.
The solar energy generation is divided into tracking type, semi-tracking type, and fixed type solar cell equipment according to the level of the change of direction along the position of the sun in order to maximize the generation capacity.
First, the tracking array is a scheme for maximizing electricity generation efficiency, and is a scheme of tracing the position of the sun through power and device operation so that the direct ray of light may become vertically incident upon the front surface of the solar cell module.
Such an automatic tracking type solar cell is divided into a position information programming system by the meridian information and an optical sensor automatic tracking system according to the type of the tracking system.
Next, the semi-tracking array is a scheme of vertically changing the tilt angle of the solar cell array according to the season or month, and is a scheme which generally changes the tilt angle seasonally.
The power output of the semi-tracking array is between the fixed type and the tracking type, and the power output is usually greater than the fixed type by about 20%.
In the above power generation system, the fixed type system is a cheap and stable structure and is widely used in places without limitation in the area of installation in a relatively remote region, and the fixed type system is generally installed in places with strong wind.
Furthermore, the tracking array has a low power generation efficiency compared to the semi-fixed type, but the initial installation costs are low and personnel expenses and risks according to the repair and maintenance are low, and thus the tracking array is relatively widely used.
Furthermore, in consideration of geographical characteristics that the installation area on the ground is not sufficient, the method of generating electricity from the solar energy using a building integrated photovoltaic system (BIPV) and supplying the electricity to consumers is also used, but there is a limit due to the shape of the building, and thus there has been a need for an efficient solar light condensation technology.
Furthermore, the photovoltaic module, which is used in the solar light power generation system, is mainly of a flat type, and the flat photovoltaic module is configured to form a unit photovoltaic module string which may generate a unit voltage which is set by serial connection of photovoltaic cells of a regular size (e.g., 125 mm×125 mm) and to generate necessary power (=current×voltage) by serial or parallel connection of a certain number of photovoltaic cells.
Hence, if the solar light is irradiated, the flat type photovoltaic module generates direct electricity which is required by the photoelectric effect of respective photovoltaic cells which form the photovoltaic strings.
Furthermore, the direct power generated by the flat type photovoltaic module is directly used or is used after being converted into alternating current using an inverter.
Furthermore, generally, the photovoltaic cell with the area size of 125 m×125 m of crystalline silicon (Si) has the electric characteristics that the open circuit voltage is about 0.6V, the short-circuit current is about 3 to 6 A, and the maximum power is generating the direct power of about 1.2 to 2.5 W according to the efficiency of the photovoltaic cell in the standard condition (the airmass of 1.5, solar radiation of 1000 W/m2, and the surface temperature of the photovoltaic cell of 25° C.).
Hence, when the efficiency of the flat type photovoltaic cell module is about 15%, the flat type photovoltaic module, in which the area of photovoltaic cells is 1 m2 in the above-stated standard condition, may generate the power of about 150 50 W.
Furthermore, the photovoltaic cells of the flat type photovoltaic module mainly use silicon (Si) which is an expensive semiconductor material, and thus the photovoltaic cells are expensive and the price of the semiconductor silicon (Si) occupies more than 50% of the module price.
Hence, there is a need for a solution to reduce the unit cost of the photovoltaic module or reduce the area of use of the photovoltaic cell for the same power, and one of the solutions is a concentrating photovoltaic module which adds a concentrating device for increasing the high optical absorption density by concentrating solar light.
However, in the conventional photovoltaic module, the unit electric power, which is generated for the unit area, increases according to the concentration ratio of the device, and thus the unit costs of the installation could be reduced only by assembling a large number of flat type modules.
Hence, there is a need for a wide space for installing the photovoltaic module, and the device needs to be installed only in an area with long daylight hours.
Furthermore, the energy, which is generated in the photovoltaic module, needs to be used to drive the photovoltaic module along the meridian of the sun, and thus the efficiency according to the energy loss decreases.